1. Field of the Invention
The present invention relates to a light emitting diode driver capable of driving a light emitting diode by converting a commercial power supply into a driving power supply.
2. Description of the Related Art
Recently, in the area of displays, a display device mainly using a cathode ray tube (CRT) has been replaced with a high-resolution large flat panel display (FPD) device, reflecting users' demands.
In particular, in the case of a large display device, demand for a liquid crystal display (LCD) has been remarkably increased due to the advantages of slimness and lightness thereof, which will solidify an LCD's leading position in terms of price and marketability in the future.
Meanwhile, in the case of an existing liquid crystal display device, a cold cathode fluorescent lamp (CCFL) has mainly been used as a backlight light source. However, the use of a light emitting diode (LED) is gradually being increased due to various advantages such as power consumption, lifespan, environmental-friendliness, efficiency, or the like.
In order to drive the light emitting diode, a power supply circuit converting commercial alternating current (AC) power into direct current (DC) power and a driving circuit controlling a supply of DC power to the light emitting diode have generally been used. The power supply circuit may be divided into a primary side and a secondary side, based on a transformer, in order to enhance an insulating function. The primary side is configured as a circuit rectifying and smoothing the commercial AC power to switch a power supply and a secondary side is configured as a circuit rectifying power transformed by the transformer and controlling the supply of the rectified power to a load. Generally, the primary side is provided with a power switching control circuit and a secondary side is provided with the driving circuit. In this case, in order to smoothly control the switching of a power supply, the power state supplied to the light emitting diode may be fed back to a power switching control circuit to control the switching based on the fed-back power state. To this end, a plurality of photo couplers including an insulating function to transfer a feedback current, have mainly been used. However, since the photo coupler is an optical device, signal transfer characteristics depend on photons, used time, and junction temperature, such that it is difficult to design a circuit and manufacturing costs may be increased due to the use of the photo coupler.